For connecting complex electronic and optical systems, which tend to become more and more compact, densely packed connection means, which also preserve the signal quality, i.e. which have a good shielding and do not present any reflections, are required. Such connecting means are today manufactured using mainly conventional fine mechanical methods.
However, U.S. Pat. No. 5,180,311 discloses an electrical interconnector comprising electrical conductor paths on a resilient elastomeric member for interconnection of multi-layer printed circuit boards.
U.S. Pat. No. 4,891,014 describes a method for obtaining electrical edge contacts using contact bumps formed on metallic contact pads.
U.S. Pat. No. 5,092,782 describes an integral elastomeric card edge electrical connector for providing shorter signal paths through the contact with reduced interference. The card edge connector is also designed to allow a high density of interconnections between different layers of multi-layer circuit cards without routing signal paths to the card surface.
When electrically connecting two systems, each having a densely packed configuration of electrical conductor paths, the lack of a structure being small enough and having a high density of contacts has become a problem. Also, the size of an individual electrical contact element is important. Thus, it is common that part of the electrical conductor line of a contact element cannot be impedance matched. However, if the portion of the conductor line not being impedance matched is shorter than approximately 1/20 of the wavelength corresponding to the highest frequency of a signal transmitted through the contact, the error imposed by the not impedance part can normally not be detected or will not affect the signal so that the information contents cannot be extracted. Thus, for an electrical contact element interconnecting transmission lines carrying signals having frequencies of 10 GHz and operating at common dielectric constants, the portion of the contact which is not impedance matched must not exceed a distance of approximately 0.5 mm.
For optical contact elements unwanted reflections and attenuation may arise at the end surface of a wave guide where the light signal is to continue to another waveguide and also at the facing end surface of this other waveguide. For minimizing these effects, the waveguides should be well aligned with their facing end surfaces as close to each other as possible. Also, placing an optically transparent homogenous material between the surfaces having a refractive close to those of the waveguides will reduce attenuation.